linux-kernel - Re: [PATCH] acpi/battery: fix wrong value of capacity_now reported by few battery types when fully charged (resend)

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Tue, 17 Jun 2014 14:09:22 +0200
From:	"Rafael J. Wysocki" <rjw@...ysocki.net>
To:	Josef Gajdusek <atx@....name>
Cc:	lenb@...nel.org, linux-acpi@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] acpi/battery: fix wrong value of capacity_now reported by few battery types when fully charged (resend)

On Thursday, June 12, 2014 04:58:13 PM Josef Gajdusek wrote:
> It seems that some batteries (noticed on DELL JYPJ136) assume 
> capacity_now = design_capacity when fully charged. This causes 
> reported capacity to suddenly jump to >full_charge_capacity (and that 
> means capacity reported to userspace is >100% and incorrect) 
> values after 99%. This patch attempts to detect this bug and trims 
> capacity_now properly.
> 
> Signed-off-by: Josef Gajdusek <atx@....name>
> ---
> Oops, I forgot to sign the previous one.
> 
> diff --git a/drivers/acpi/battery.c b/drivers/acpi/battery.c
> index e48fc98..3338dd5 100644
> --- a/drivers/acpi/battery.c
> +++ b/drivers/acpi/battery.c
> @@ -532,6 +532,14 @@ static int acpi_battery_get_state(struct acpi_battery *battery)
>  			" invalid.\n");
>  	}
>  
> +	/* When fully charged, some batteries wrongly report
> +	 * capacity_now = design_capacity instead of = full_charge_capacity
> +	 */
> +	if (battery->capacity_now == battery->design_capacity &&

Why don't you use the

	battery->capacity_now > battery->full_charge_capacity

check here?  That would be more robust, wouldn't it?

> +	    battery->full_charge_capacity != ACPI_BATTERY_VALUE_UNKNOWN)
> +		battery->capacity_now = battery->full_charge_capacity;
> +
> +
>  	if (test_bit(ACPI_BATTERY_QUIRK_PERCENTAGE_CAPACITY, &battery->flags)
>  	    && battery->capacity_now >= 0 && battery->capacity_now <= 100)
>  		battery->capacity_now = (battery->capacity_now *
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-acpi" in
> the body of a message to majordomo@...r.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/